1. Field of the Invention
The present invention relates generally to an auxiliary steering device for a vehicle and, more particularly, to the auxiliary steering device with a steering pedal. The auxiliary steering device controls a steering wheel of a main steering system by causing a reciprocation angular motion of the steering pedal converted into a rotating motion of a steering drive shaft, thereby making possible the steering for a vehicle by either the hand-operated steering wheel or the foot-operated steering pedal.
2. Description of the Prior Art
In the prior art, there have been proposed vehicles with auxiliary steering devices as disclosed in U.S. Pat. Nos. 4,726,441 and 4,756,552 and Japanese Patent Laid-open Publication No. Sho. 60-174,363. Each of the vehicles disclosed in the above U.S. patents is provided with a steering system controlled by either a pair of steering wheels, that is, a main steering wheel and an auxiliary steering wheel. The vehicle disclosed in the above Japanese patent is provided with a main steering system having a main steering wheel, as well as an auxiliary steering system having an auxiliary steering handle. In operation of the vehicles disclosed in the above U.S. patents, two operators may sit on opposed sides of the cab respectively in order to selectively operate one of two steering wheels of the steering system. When there is only one operator controlling the steering system, the operator needs to sit on either side of the cab in order to operate either steering wheel of the steering system. The typical steering system having the auxiliary steering wheel or handle, as well as the main steering wheel, require controlling by hand.
As the typical steering systems for vehicles only have the hand-operated steering means, the steering systems cannot allow the operators to be free from hand operation for the steering means during driving of the vehicles even when the operators are tired from driving for a long time. Moreover, it is very difficult to use a portable phone, control the stereo system, enjoy something to eat, drink or smoke, by using one's hands while operating the vehicle. When the operator temporarily separates the hands from the steering wheel or controls the steering wheel using the elbows instead of the hands in order to free the hands for other use, a serious traffic accident may result.
Japanese Utility Model Laid-open Publication No. Sho. 62-97,878 discloses a power steering system with an auxiliary steering device as well as a hand-operated steering wheel, and whose auxiliary steering device has a foot-operated steering pedal for controlling the steering system using one's foot. The above steering system can be thus controlled by either the hand-operated steering wheel or the foot-operated steering pedal. In the above steering system suitable for being used in construction vehicles such as power shovels, the bottom end of a steering drive shaft extending from the steering wheel is coupled to both a metal valve and a booster fixed to a bracket plate of the cab of the vehicle, such that the steering system can be controlled by the steering wheel. In addition, the auxiliary steering device of the steering system includes a casing provided about the lower section of a steering drive shaft column and a driven gear fixed to the bottom end section of the steering drive shaft above the bracket plate. The auxiliary steering device also includes a hydraulic motor mounted to the casing, which hydraulic motor has a drive gear gearing into the driven gear fixed to the bottom end section of the steering drive shaft. The hydraulic motor is connected to a hydraulic pump through a hydraulic line, and the middle portion of the hydraulic line is provided with the foot-operated steering pedal. With the above structure, the power steering cylinder of the above steering system can be controlled by either the hand-operated steering wheel or the foot-operated steering pedal, thus to steer the wheels of the vehicle.
However, the above auxiliary steering device having the foot-operated steering pedal is mainly used for the power steering system so that the device has a complicated construction including the hydraulic cylinder, the hydraulic pump, the valves and the like. With the complicated construction of the auxiliary steering device, the above steering system is scarcely used for small-sized or middle-sized automobiles. Furthermore, as the above steering system is a power steering system, the steering power is not directly applied to the wheels of the vehicle, so that the steering system is not suitable for steering the wheels by working the foot-operated steering pedal during a high speed traveling of the vehicle such as on a high way, and this may cause trouble for the steering system while in operation.
If briefly described, the typical steering systems with the auxiliary steering devices having foot-operated steering pedals are not suitable for use in high speed vehicles but merely used in hydraulic heavy vehicles such as construction vehicles and agricultural vehicles during low speed traveling. The vehicles suitable for high speed travelling have only the steering wheels for a steering system, so that the steering systems cannot help being controlled by hands and thereby having the above-mentioned problems.